JP2019147196A - Robot hand, robot, and method for adjusting hand width of robot hand - Google Patents

Abstract

To make the hand width adjustable and realize weight reduction and simplified structure.SOLUTION: The robot hand includes: a pair of movable members 7A, 7B detachable mounted to a wrist flange of the robot body, the movable members being spaced apart from each other; holding parts 8, 9 respectively mounted to the movable members 7A, 7B to hold a workpiece; and a width adjustment mechanism 10 supporting the pair of movable members 7A, 7B in a relatively movable manner to adjust the spacing B between the pair of movable members 7A, 7B by relative movement of the pair of movable members 7A, 7B in a width direction A. The pair of movable members 7A, 7B move relatively in the width direction A when the width adjustment mechanism 10 is operated by motion of the robot body or by an operator.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a robot hand, a robot, and a hand width adjusting method of the robot hand.

  Conventionally, a power source such as an air cylinder or an electric actuator has been used to change the hand width of a robot hand (see, for example, Patent Documents 1 to 3). In Patent Documents 1 and 2, a power source is mounted on a robot hand. In Patent Document 3, in order to reduce the weight of the robot hand, the driving force of a power source independent of the robot hand is used for changing the hand width.

JP 2008-137107 A Japanese Patent No. 4495509 JP 2006-272526 A

  In the case of Patent Documents 1 and 2, there is a disadvantage that the weight of the robot hand increases by the weight of the power source and the portable weight of the robot hand decreases by the weight of the power source. In the case of Patent Document 3, it is suitable for reducing the weight of the robot hand, but there is a disadvantage in that a member such as wiring for transmitting a driving force from the power source to the robot hand is required and the structure becomes complicated.

  The present invention has been made in view of the above-described circumstances, and is a robot hand that can adjust the hand width, and can realize weight reduction and simplification of the structure, and the hand width of the robot hand. The purpose is to provide an adjustment method.

In order to achieve the above object, the present invention provides the following means.
A first aspect of the present invention is a pair of movable members that can be attached to and detached from a wrist flange of a robot main body and are arranged with a space between each other, and a holding unit that is provided on each of the pair of movable members and holds a workpiece And the pair of movable members are supported so as to be relatively movable in the width direction that is the arrangement direction of the pair of movable members, and the distance between the pair of movable members is increased by the relative movement of the pair of movable members in the width direction A robot hand that is relatively moved in the width direction by an operation of the width adjustment mechanism by an operation of the robot body or an operation of the width adjustment mechanism by an operator. is there.

According to this aspect, the pair of movable members are arranged with a space therebetween. Therefore, the workpiece can be stably held by the holding portion provided in each movable member. Further, the width of the hand, which is the distance between the pair of movable members, can be adjusted by the width adjusting mechanism. Therefore, by adjusting the hand width according to the width of the work, the work having various dimensions can be held by the holding unit.
In this case, the relative movement of the pair of movable members is not a power source such as an air cylinder or an electric actuator, but is performed by the operation of the width adjusting mechanism by the robot body or an operator, so that a power source is unnecessary. Thereby, the weight reduction and simplification of the structure of the robot hand can be realized.

In the first aspect, the width adjusting mechanism may include a lock mechanism that fixes a relative position of the pair of movable members in the width direction.
When the hand width is not adjusted, the relative position of the pair of movable members is fixed by the lock mechanism, so that the pair of movable members move unintentionally and the hand width changes unintentionally. Can be prevented.

In the first aspect, the lock mechanism may have a knob that is operated by the robot body or the operator, and may include a thumbscrew that fixes the pair of movable members to each other.
The robot body or the operator can fix the pair of movable members to each other by rotating the knob in the direction in which the thumbscrew is tightened (lock direction). Further, the robot body or the operator can release the fixation of the pair of movable members by rotating the knob in the direction in which the thumbscrew is loosened (unlock direction). In this manner, the pair of movable members can be fixed and unlocked with a simple operation.

In the first aspect, the lock mechanism may include a knob hook portion that is attached to the wrist flange and engages with the knob.
With this configuration, the knob can be rotated by the operation of the robot body. That is, with the pair of movable members removed from the wrist flange, the robot body engages the knob hook portion attached to the wrist flange with the knob, and then rotates the wrist flange around the knob hook portion, The knob can be rotated.

In the first aspect, the width adjusting mechanism may include a rack provided on one of the pair of movable members and a pinion provided on the other of the pair of movable members. .
With this configuration, the pair of movable members can be relatively moved by the rack moving while rotating the pinion only when a force equal to or greater than a predetermined threshold in the width direction is applied to the pair of movable members.

In the first aspect, the width adjusting mechanism may include a gear that meshes with the pinion and is rotated by the robot body or the operator.
When the gear rotates, the rotation of the gear is transmitted to the pinion, the rack moves in the width direction by the rotation of the pinion, and the pair of movable members relatively move in the width direction by the movement of the rack. That is, the robot body or the operator can adjust the hand width by rotating the gear. Further, the adjustment amount of the hand width can be accurately controlled by the rotation amount of the gear.

In the first aspect, the width adjusting mechanism may include a movable member hooking portion that is attached to the wrist flange and engages with a part of one of the pair of movable members.
With this configuration, the hand width can be adjusted by moving one movable member in the width direction by the operation of the robot body. That is, with the pair of movable members removed from the wrist flange, the robot body engages the movable member hooking portion attached to the wrist flange with a part of one movable member, and moves the wrist flange in the width direction. Thus, one movable member can be moved.

A second aspect of the present invention includes a robot main body having a wrist flange, any one of the robot hands described above, and a control device that controls the robot main body, and the control device includes the pair of movable members. It is a robot that causes the robot body to execute an operation of relative movement in the width direction.
In the second aspect, the control device causes the robot body to perform an operation of removing the pair of movable members from the wrist flange, and then performs an operation of relatively moving the pair of movable members in the width direction. You may make the said robot main body perform.

A third aspect of the present invention is the hand width adjustment method for a robot hand according to any one of the above, wherein the robot main body relatively moves the pair of movable members in the width direction. Is the method.
In the third aspect, the robot body may remove the pair of movable members from the wrist flange, and then relatively move the pair of movable members in the width direction.

  According to the present invention, it is possible to adjust the hand width, and it is possible to realize the weight reduction and the simplification of the structure.

1 is an overall configuration diagram of a robot according to an embodiment of the present invention. It is a perspective view which shows the whole structure of the slave side unit of the robot hand which concerns on one Embodiment of this invention. It is a figure explaining the holding | maintenance method of the workpiece | work by the robot hand of FIG. It is a figure explaining the other holding | maintenance method of the workpiece | work by the robot hand of FIG. It is a figure explaining the fixing operation | movement of a pair of frame by the robot main body of FIG. 1, and fixing release operation | movement. It is a figure explaining the fixing operation | movement of a pair of frame by the robot main body of FIG. 1, and fixing release operation | movement. It is a figure explaining the adjustment operation | movement of the hand width by the robot main body of FIG. It is a figure explaining the adjustment operation | movement of the hand width by the robot main body of FIG.

Hereinafter, a robot hand 1, a robot 100, and a hand width adjusting method for a robot hand according to an embodiment of the present invention will be described with reference to the drawings.
A robot 100 according to the present embodiment includes a robot body 2, a robot hand 1 attached to the robot body 2, and a control device 3 that controls the robot body 2.

  The robot body 2 is a robot generally used for transporting the workpiece W. FIG. 1 shows, as an example, a 6-axis articulated robot body 2 having joint axes J1 to J6. The robot body 2 may be another type of robot such as a SCARA robot or a parallel link robot. The robot body 2 includes an arm 4, and a wrist flange 5 to which the robot hand 1 can be attached is provided at the tip of the arm 4. The robot body 2 can move the wrist flange 5 three-dimensionally by the operation of the arm 4.

  As shown in FIGS. 1 to 4, the robot hand 1 includes tool changers 6A and 6B, a pair of frames (movable members) 7A and 7B arranged with a space therebetween, and a pair of frames 7A and 7B. A suction pad (holding portion) 8 and a roller (holding portion) 9 that are provided in each of them and hold a workpiece W, and a width adjusting mechanism 10 that supports the pair of frames 7A and 7B so as to be relatively movable in the width direction A are provided. Yes. The width direction A is an arrangement direction of the pair of frames 7A and 7B.

  The tool changer includes a master plate 6A attached to the wrist flange 5 of the robot body 2, and a master plate 6A and a detachable slave plate 6B. The robot body 2 can attach / detach the slave plate 6B to / from the master plate 6A by sending air pressure or an electric signal to the master plate 6A via an air circuit or an electric circuit (not shown).

  As shown in FIGS. 2 to 4, the pair of frames 7 </ b> A and 7 </ b> B are each linear and parallel to each other. One frame 7 </ b> A is a fixed frame fixed to the slave plate 6 </ b> B via the fixed plate 12. The fixed plate 12 is fixed to the slave plate 6B and the fixed frame 7A. The other frame 7B is a movable frame 7B supported by the width adjusting mechanism 10 so as to be movable in the width direction A with respect to the slave plate 6B and the fixed frame 7A.

In a state where the pair of frames 7A and 7B are attached to the wrist flange 5 via the tool changers 6A and 6B, the width direction A is orthogonal to the central axis (sixth axis J6) of the wrist flange 5. When the work W is transported, the wrist flange 5 is normally directed downward and the pair of frames 7A and 7B are arranged horizontally. Hereinafter, the slave plate 6B side is defined as the upper side of the frames 7A and 7B, and the opposite side of the slave plate 6B is defined as the lower side of the frames 7A and 7B.
The movable frame 7B has a width adjustment guide 13 protruding upward from the upper surface thereof. The width adjustment guide 13 may be a plate-like member as shown in the drawings, or may be a member having any other shape.

  The suction pads 8 are provided at a plurality of positions spaced from each other in the longitudinal direction of the fixed frame 7A. Similarly, the suction pads 8 are provided at a plurality of positions spaced from each other in the longitudinal direction of the movable frame 7B. Each suction pad 8 is provided at a position protruding downward from the lower surfaces of the frames 7A and 7B, and, as shown in FIG. 3, sucks onto the upper surface of the work W disposed below the frames 7A and 7B.

  The rollers 9 are provided at a plurality of positions spaced from each other in the longitudinal direction of the fixed frame 7A. Similarly, the rollers 9 are provided at a plurality of positions spaced from each other in the longitudinal direction of the movable frame 7B. Each roller 9 is rotatable about a rotation axis in the width direction A, and supports the lower surface of the end portion of a thin flat work W such as a printed board as shown in FIG. The workpiece W placed on the roller 9 can slide in the longitudinal direction of the frames 7A and 7B while rotating the roller 9.

  The width adjusting mechanism 10 includes two linear shafts 15 arranged along the width direction A and two guide bushes 16 for guiding the linear shaft 15 in the longitudinal direction. The two linear shafts 15 are arranged at intervals in the longitudinal direction of the frames 7A and 7B. One end of each linear shaft 15 is fixed to the movable frame 7B. The guide bush 16 is a cylindrical member fixed to the fixed plate 12. The linear shaft 15 penetrates the guide bush 16 in the longitudinal direction, and can move smoothly in the longitudinal direction with respect to the guide bush 16. When an external force in the width direction A acts on the movable frame 7B, the linear shaft 15 smoothly moves in the guide bush 16 so that the movable frame 7B moves smoothly in a direction toward or away from the fixed frame 7A. . As a result, the hand width B, which is the distance between the pair of frames 7A and 7B, changes steplessly.

The width adjusting mechanism 10 includes a lock mechanism 11 that fixes the relative position in the width direction A of the pair of frames 7A and 7B. The lock mechanism 11 includes a guide rail 17 that extends in the width direction A between the movable frame 7B and the fixed plate 12, and a thumbscrew 18 that fixes the pair of frames 7A and 7B to each other.
The guide rail 17 has a linear slit 17a extending in the width direction A. One end of the guide rail 17 is fixed to the movable frame 7B.
The thumbscrew 18 has a male screw (not shown) and a handle portion 18a that is a knob connected to one end of the male screw. A guide rail 17 is sandwiched between the handle portion 18 a and the fixed plate 12. A male screw of the thumbscrew 18 passes through the slit 17 a and is fastened to a female screw formed on the fixed plate 12.

By rotating the thumbscrew 18 in the tightening direction (locking direction), the guide rail 17 is fixed to the fixed plate 12, whereby the movable frame 7 B is fixed to the fixed frame 7 A and the hand width B is constant. Maintained.
On the other hand, rotation of the thumbscrew 18 in the loosening direction (unlock direction) releases the fixing of the guide rail 17 to the fixed plate 12, thereby enabling the movable frame 7B to move relative to the fixed frame 7A. B can be changed. In the unlocked state, the guide rail 17 together with the linear shaft 15 moves smoothly in the longitudinal direction with respect to the thumbscrew 18. Therefore, the pair of frames 7A and 7B can be fixed to each other at an arbitrary relative position by the thumbscrew 18, and the hand width B can be maintained at an arbitrary width.

  As shown in FIGS. 5 and 6, the width adjusting mechanism 10 further includes a hook 18 a for operating the knob 18 a and the width adjusting guide 13 (knob hooking portion, movable member hooking portion) 19. The hook portion 19 has a concave portion 19a that engages with both the width adjustment guide 13 and the handle portion 18a. The hook portion 19 is attached to the wrist flange 5 of the robot body 2.

  As described above, the robot hand 1 includes the master plate 6A, the hook unit 19, and the master side unit that is always attached to the wrist flange 5 during the operation of the robot body 2, the slave plate 6B, the frames 7A and 7B, and the width adjustment. It comprises a slave-side unit that includes the mechanism 10 and is attached to and detached from the wrist flange 5 as required during the operation of the robot body 2.

  The control device 3 includes a storage unit (not shown) and a processor (not shown). The storage unit stores a hand width adjustment program for causing the robot body 2 to perform the operation of adjusting the hand width B of the robot hand 1. The processor automatically adjusts the hand width B according to the width of the workpiece W to be held by controlling the robot body 2 according to the hand width adjustment program.

Next, a hand width adjustment operation (hand width adjustment method) by the robot body 2 will be described.
First, the robot body 2 removes the slave side unit from the wrist flange 5 by placing the slave side unit attached to the wrist flange 5 at a predetermined location and separating the slave plate 6B from the master plate 6A.

  Next, the robot body 2 operates the arm 4 to engage the hook portion 19 of the wrist flange 5 with the handle portion 18a as shown in FIG. Next, as shown in FIG. 6, the robot body 2 operates the arm 4 to rotate the wrist flange 5 around the hook portion 19 in the unlocking direction. Thereby, the handle | steering-wheel part 18a and the thumbscrew 18 rotate in an unlocking direction, and fixation of the movable frame 7B with respect to the fixed frame 7A is cancelled | released.

  Next, the robot body 2 engages the hook 19 with the width adjustment guide 13 by operating the arm 4. Next, as shown in FIGS. 7 and 8, the robot body 2 moves the wrist flange 5 in the width direction A by moving the arm 4. As a result, the width adjusting guide 13 and the movable frame 7B move linearly in the width direction A with respect to the fixed frame 7A, and the hand width B changes. The amount of change in the hand width B is controlled by the amount of movement of the wrist flange 5 in the width direction A. FIG. 7 shows a case where the movable frame 7B is brought close to the fixed frame 7A. FIG. 8 shows a case where the movable frame 7B is separated from the fixed frame 7A.

  Next, the robot body 2 operates the arm 4 to re-engage the hook portion 19 of the wrist flange 5 with the handle portion 18a as shown in FIG. Next, as shown in FIG. 5, the robot body 2 rotates the wrist flange 5 around the hook portion 19 in the locking direction by operating the arm 4. As a result, the handle portion 18a and the thumbscrew 18 rotate in the locking direction, the movable frame 7B is fixed again to the fixed frame 7A, and the hand width B is maintained constant.

  Thus, according to the present embodiment, the pair of frames 7A and 7B are configured to be relatively moved in the width direction A by the operation of the width adjusting mechanism 10 by the operation of the robot body 2. Further, the relative position of the pair of frames 7A and 7B is fixed and released by the operation of the lock mechanism 11 by the operation of the robot body 2. That is, the robot hand 1 is not provided with a power source for adjusting the hand width B, such as an air cylinder or an electric actuator. Thereby, the robot hand 1 can be reduced in weight. In addition, since a structure such as wiring for transmitting the driving force for adjusting the hand width B to the slave side unit of the robot hand 1 is unnecessary, the structure can be simplified.

  The hand width B is automatically adjusted by the control of the robot body 2 by the control device 3. That is, the operator does not need to adjust the hand width B. Accordingly, unmanned operation is possible even when various workpieces W having different sizes are transported using the same robot hand 1, and this is particularly advantageous in continuous operation in an unattended state such as overnight operation.

In the present embodiment, when the force in the width direction A acting on the movable frame 7B is less than a predetermined threshold, the width adjusting mechanism 10 prevents the movement of the movable frame 7B in the width direction A and acts on the movable frame 7B. There may be provided means for allowing movement of the movable frame 7B in the width direction A when the force in the width direction A is equal to or greater than a predetermined threshold. By providing such means, it is possible to prevent the movable frame 7B from moving unintentionally due to vibration or the like.
For example, the means may be friction between the outer peripheral surface of the linear shaft 15 and the inner peripheral surface of the guide bush 16.

Alternatively, the means may include a rack provided on one of the pair of frames 7A and 7B and a pinion provided on the other of the pair of frames 7A and 7B and meshing with the rack. For example, the rack is fixed to the movable frame 7B, and moves in the width direction A as the movable frame 7B moves. The rack may be provided on the linear shaft 15. The pinion is fixed to the fixed frame 7A, for example. The hand width B can be adjusted in units of rack teeth.
The rack and pinion also function as a lock mechanism that fixes the movable frame 7B to the fixed frame 7A when the force in the width direction A acting on the movable frame 7B is less than a predetermined threshold.

  The width adjusting mechanism 10 may further include a gear that meshes with the pinion. When the robot body 2 rotates the gear using a predetermined tool such as an electric screwdriver or a nutrunner, the rotation of the gear is transmitted to the pinion, and the rack and the movable frame 7B move in the width direction A by the rotation of the pinion. . The amount of movement of the movable frame 7B is controlled by the amount of gear rotation. The tool for rotating the gear may be attached to the wrist flange 5 similarly to the hook portion 19 or may be detachable from the wrist flange 5 via another slave plate. In order to prevent the gear from rotating unintentionally at times other than during the rotation operation by the robot body 2, the rotation of the gear may be configured to be decelerated by the pinion.

In the present embodiment, the hook portion 19 is attached to the wrist flange 5 of the robot body 2, but instead, the hook portion 19 may be provided independently of the robot body 2. For example, the hook portion 19 may be fixed around the robot body 2.
In this case, the rotation of the handle portion 18 a and the adjustment of the hand width B are executed in a state where the slave side unit is attached to the wrist flange 5.

Specifically, the robot body 2 engages the handle portion 18a with the hook portion 19 by operating the arm 4 in a state where the slave side unit is attached to the wrist flange 5, and then the hook portion 19 And the wrist flange 5 is rotated in the unlocking direction around the handle portion 18a. Thereby, the fixation of the movable frame 7B with respect to the fixed frame 7A is released.
Next, the robot body 2 operates the arm 4 to engage the width adjustment guide 13 with the hook portion 19, and then moves the wrist flange 5 linearly in the width direction A to adjust the hand width B.
Next, the robot body 2 operates the arm 4 to re-engage the handle portion 18a with the hook portion 19 and then rotates the wrist flange 5 around the hook portion 19 and the handle portion 18a in the locking direction. Thereby, the movable frame 7B is fixed to the fixed frame 7A.

  When the width adjusting mechanism 10 includes a gear, a tool such as a driver or a nutrunner may be fixed around the robot body 2. In this case, the robot body 2 fits the tool on the gear by operating the arm 4 with the slave unit attached to the wrist flange 5, and then rotates the wrist flange 5 around the gear. Thus, the hand width B can be adjusted.

  In the present embodiment, the common hook portion 19 is used for the handle portion 18a and the width adjustment guide 13, but instead, a hook portion dedicated to the handle portion 18a and a hook portion dedicated to the width adjustment guide 13 are provided. It may be provided.

  In the present embodiment, the movable frame 7B is provided with the width adjustment guide 13, but the width adjustment guide 13 is not necessarily provided. That is, the hook portion 19 may be engaged with a part of the movable frame 7B or another structure fixed to the movable frame 7B.

  In the present embodiment, the lock mechanism 11 includes the thumbscrew 18 as means for fixing the relative positions of the pair of frames 7A and 7B. However, instead of this, other means may be provided. For example, the lock mechanism 11 may include a push button switch, and the pair of frames 7A and 7B may be fixed and released when the robot body 2 presses the push button switch.

In the present embodiment, only one of the pair of frames 7A and 7B is movable in the width direction A. Instead, both the frames 7A and 7B are movable in the width direction A. May be. By moving the pair of frames 7A and 7B substantially symmetrically in the width direction A with respect to the tool changers 6A and 6B, the position of the center of gravity of the entire robot hand 1 can be stabilized.
In addition, another pair of frames that are relatively movable in the longitudinal direction of the pair of frames 7A and 7B may be provided. That is, four frames may be arranged to form a quadrangle, and the hand width B may be adjusted in two directions orthogonal to each other.

  In the present embodiment, the suction pad 8 and the roller 9 are provided as the holding unit that holds the workpiece W. However, the type of the holding unit can be appropriately changed according to the workpiece W to be held. For example, a magnet, a hook, a chuck claw for an outer diameter chuck or an inner diameter chuck may be adopted as the holding portion.

In the present embodiment, the robot body 2 operates the movable frame 7B to adjust the hand width B, but instead, the operator manually operates the movable frame 7B to adjust the hand width B. May be.
In this embodiment, the robot body 2 operates the lock mechanism 11 to fix and release the movable frame 7B, but instead, the operator manually operates the lock mechanism 11. The movable frame 7B may be fixed and released.
In the present embodiment, a robot different from the robot body 2 to which the robot hand 1 is attached may execute the movement of the movable frame 7B and the operation of the lock mechanism 11.

DESCRIPTION OF SYMBOLS 1 Robot hand 2 Robot main body 3 Control apparatus 4 Arm 5 Wrist flange 6A, 6B Tool changer 7A, 7B Frame (movable member)
8 Suction pad (holding part)
9 Roller (holding part)
DESCRIPTION OF SYMBOLS 10 Width adjustment mechanism 11 Lock mechanism 12 Fixed plate 13 Width adjustment guide 15 Linear shaft 16 Guide bush 17 Guide rail 18 Thumb screw 18a Handle part 19 Hook part (knob hook part, movable member hook part)
19a Concave part 100 Robot

Claims (11)

A pair of movable members that can be attached to and detached from the wrist flange of the robot body, and are arranged at intervals from each other;
A holding portion that is provided in each of the pair of movable members and holds a workpiece;
The pair of movable members are supported so as to be relatively movable in a width direction that is an arrangement direction of the pair of movable members, and an interval between the pair of movable members is adjusted by relative movement of the pair of movable members in the width direction. Width adjustment mechanism,
A robot hand in which the pair of movable members are relatively moved in the width direction by operation of the width adjustment mechanism by operation of the robot body or operation of the width adjustment mechanism by an operator.   The robot hand according to claim 1, wherein the width adjusting mechanism includes a lock mechanism that fixes a relative position of the pair of movable members in the width direction.   The robot hand according to claim 2, wherein the lock mechanism includes a knob that is operated by the robot main body or the operator and includes a thumbscrew that fixes the pair of movable members to each other.   The robot hand according to claim 3, wherein the lock mechanism includes a knob hook portion that is attached to the wrist flange and engages with the knob.   The width adjustment mechanism includes a rack provided on one of the pair of movable members and a pinion provided on the other of the pair of movable members and meshing with the rack. Robot hand.   The robot hand according to claim 5, wherein the width adjusting mechanism includes a gear that meshes with the pinion and is rotated by the robot body or the operator.   The robot hand according to any one of claims 1 to 6, wherein the width adjusting mechanism includes a movable member hooking portion that is attached to the wrist flange and engages with a part of one of the pair of movable members. A robot body having a wrist flange;
The robot hand according to any one of claims 1 to 7,
A control device for controlling the robot body,
A robot that causes the robot body to perform an operation in which the control device relatively moves the pair of movable members in the width direction.   The control device causes the robot body to perform an operation of removing the pair of movable members from the wrist flange, and then causes the robot body to perform an operation of relatively moving the pair of movable members in the width direction. 8. The robot according to 8. A hand width adjustment method for a robot hand according to any one of claims 1 to 7,
A hand width adjustment method for a robot hand in which the robot body relatively moves the pair of movable members in the width direction.   11. The hand width adjustment method for a robot hand according to claim 10, wherein the robot body removes the pair of movable members from the wrist flange, and then relatively moves the pair of movable members in the width direction.

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